Nowadays, semiconductor devices are frequently used in a variety of electronic applications, such as personal computers and cellular phones, for example. One such semiconductor device widely used in electronic systems for storing data is a semiconductor memory (for example, an XtraROM, a charge trapping memory, a non-volatile memory and an embedded memory).
Memory devices such as the XtraROM, the charge trapping memory, the non-volatile memory and the embedded memory are typically arranged in an array of memory cells. A memory cell typically includes an access field effect transistor (FET) and a storage capacitor. A source/drain region of the cell access FET is coupled to a bitline, and the other source/drain region is coupled to a plate of a respective storage capacitor. The other plate of the capacitor is coupled to a common plate reference voltage. The gate of the transistor is coupled to a wordline. The storing and accessing of information into and from memory cells are achieved by selecting and applying voltages to the wordlines and bitlines.
In fabricating semiconductor devices such as the XtraROM, the charge trapping memory, the non-volatile memory and the embedded memory, the wordline bridge is a problem frequently encountered and this problem needs to be overcome to improve the reliability of these memory devices.
The wordline bridge can be overcame by etch. However, the profile would be re-entrant after etch, and it is hard to well control the device reliability when the device is scaling down. Hot standard clean 1 (SC1) can be used to isotropic etch the POLY and hence reduce the wordline bridge rate for the productions of the memory devices such as the XtraROM, the charge trapping memory, the non-volatile memory and the embedded memory. However, the hot SC1 would etch the metal-silicide layer such as a WSi layer simultaneously and cause the resistances increased.
Keeping the drawbacks of the prior arts in mind, and employing experiments and research full-heartily and persistently, the applicants finally conceived a method for reducing a wordline bridge rate.